Process for producing highly storageproof bleaching powder



Aug. 22, 1933. M. JAEGER 1,923,210

PROCESS FOR PRODUCING HIGHLY STORAGEPROOF BLEACHING POWDER Filed Oct. 21, 1930 Jwoantoc Patented Aug. 22, r V

UNITED STATES PATENT OFFICE V v 1,923,210 w T Q i PROCESS FOR. PRODUCING HIGHLY STOR- H AGEPROOF BLEACHING POWDER Max JaegenBittei-feld, Germany, assignor to I. G. Farbenindustrie :Aktiengesellschaft, Frankfort-on-the-Main, Germany Application October 21, 1930, Serial No. 490,322, and in Germany October 26, 1929 3 Claims. (01. 23-86) The present invention relates to a process of heatedto temperatures of at least about 150 C. producing highly storage-proof bleaching powand preferably between 160-180? C. der. In carrying out the present invention it is essen- It is generally acknowledged that the storing tial that the bleaching powder should be brought qualities of bleaching powder are greatly infiuinto sudden contact with the heated air in a state enced by its water content, 1. e. the lower the of high dispersion and should be separated from latter the better the bleaching powder will be the drying air after a period of time amounting capable of prolonged storing without an appreto, at the most a few seconds. Generally, even ciable loss of available chlorine. In order to profractions of a second will be sufficient to effect '10 duce bleaching'p'owder containing a minimum drying of the bleaching powder to the desired 35 of moisture, methods are employed on the one degree. The efiiciency of this method of drying hand consisting in drying the finished bleaching is probably due to the fact that all the particles powder whereas other methods aim at eliminatof the bleaching powder are individually and siing the water resulting from'the chlorinating remultaneously enveloped bythe highly heated air li action in the course of the reaction itself. which thus abruptly withdraws the moisture con- Thus it has been proposed, for example, to tained in the bleaching powder-be it sensible dry the finished bleaching powder by spreading moisture or water of crystallization-while beit on trays or moving it through tubes by means coming more or less saturated with moisture itself. of spiral blades or worm-conveyors and. simul- In consequence, it is advisable to employ a large 20 taneously subjecting the product to a counterexcess of dried heated air free from carbon dioxcurrent of heated air whose temperature may ide for the present purpose. The amount of be raised to between 105 and 115 C. These bleaching powder introduced into the drying approcesses, however, involve the drawback that paratus and .the velocity of air supplied thereto the dehydration of the bleaching powder rer p tiv ly a pr f r y regulated in s ch a 25 mains more or less incomplete whereas at the manner that the dried bleaching powder issues so same time a somewhat extensive decomposition from the dry device at temperatnre e w of the bleaching powder takes place. This is 0 C- so 8- t obviate y Subsequent reaction. due to the fact that in all these procedures the the bleaching powder, after being separated from heated air is caused to act upon a layer of bleachthe heated i preferably p y Cooled 'dOWn 0 mg powder which has an appreciable depth and to ordinary temperatures. i that the water content of the layer is to a cer- 1 carrying 011?? the Present invention t e vatain degree only displaced within, but not enr u k wn app mp y f dry n tirely removed from, the entire layer. Th r moist salts in a heated current of air may be made sult of these drying processes therefore consists The accompanying drawing which is 3 largely in a local concentration of the water con- P y ag at c 'ShOWS by way of. examp tent which promotes decomposition in the afa preferable arrangement of units p d e fected parts of the layer the more, the longer Carrying ut t e invention. it is subjected to the action of heat. The undried bleaching powder is charged into An object of the present invention, therefore, the device y the h pp 1 and is immediately 15 to dehydrate bleaching powder by means of taken up by a current of air heated t0 the tema method which obviates the above difiiculties, p as described above and issuing om and, therefore, results-in an efiicient drying of e heater 2- The Suspension then Pa s the bleaching powder with a minimum decomt ro a fan 3 tangentially into the d y g position 1' th latte chamber 4. After a few revolutions in its upper 5 I have observed that the decomposition of P 6; after 8 Very Short P the carrying bleaching powder, when ubje t d t h ti 1 capacity of the current of air is exhaustemwheredecidedly a function of the time and that,.when 1110011 the p les of dried salt sink to the conical dehydration of the bleaching powder 1 1 bottom of chamber 4, and the air which has taken is extremely accelerated, decomposition accordup Practically all the s ur contained in the (1 ingly a roaches a. minimum According t t salt, issues by means of the central funnel 5. The 0 present invention, therefore, bleaching powder Settled particles of Salt then fall into d produced by any of the known methods is, in which is p i d fr m time to time. a state of extremely fine subdivision, momen- Exam le tarily exposed to a current of air passing in I p the same direction, said current of air being 10 parts. of bleaching powder containing 36 vperature averaging about 170 C.

percent of available chlorine and about 9 percent of water are subjected to the process'as described while applying a current of air heated to a temdrled bleaching powder containing from 37 to '38 percent of available chlorine and about 1 per cent of water are obtained.

Iclaim:

1. A process for producing highly storage-y sud-- proof bleaching powder which comprises denly contacting undried. finely divided bleachlng powderin a state of high dispersion with a current of air heated to at least about 150 (3., and thereby suspending the powder in the air and after a periodnot exceeding a few seconds separating the bleaching powder from said heated 9 parts of 2. A process for producing highlystorageproof bleaching powder which comprises suddenly contacting undried finely divided bleaching powder in a state of high dispersion with a current of air traveling in the same direction and heated to at least about 150? C.,-and after a period not exceeding a few seconds separating the undried finely divided bleaching 

